The present invention relates generally to database management in a signaling transfer point (STP) for a common channel signaling network, and more particularly to a method for restoring data in a payload processor database of an STP.
Common Channel Signaling (CCS) provides a dedicated supervisory network for segregating signaling information from voice and data information in a telecommunications network. CCS was developed to meet the increased demands placed on the public telecommunications network by the growing market for voice, data, and information services. Previous signaling systems sent call setup and routing information over the same trunk circuit used for voice transmission. With CCS, a single out-of-band channel conveys signaling information relating to call setup, routing, and network management, among other things. Signaling System No. 7(SS7), an international protocol standard for CCS communications, creates a universal format for communicating signaling information in a CCS network (CCS7).
CCS7 networks also provide numerous advanced features for telecommunications users. By enabling communication between processors in central offices, CCS7 permits on-line or external databases to be queried. This capability opens access to such features as network-wide automated calling card service, Advanced Intelligent Network-based residential and business services, Custom Local Area Signaling Services, and Virtual Private Networking. Other advantages provided by CCS7 include Calling Number/Name Delivery and Automatic Callback to work across an entire network rather than just between subscribers served by the same central office.
Signaling transfer points (STPs) provide a key function in processing the signaling used in telecommunications. Large embedded databases, such as payload databases, have become major components in the architecture of telecommunications switches "payload database" and "real time database" refer to the same entity throughout. Payload databases used in STPs are embedded databases accessible to processing logic along a payload path. These databases store tens of thousands, even millions, of data entries for use in processing network traffic and must permit high-speed retrieval of the data by the system.
A critical aspect of STPs for SS7 networks is the speed of recovery after a failure occurs or upon start-up. STPs are key components of large telecommunications networks. Consequently, reducing the time that an STP is out of service is a major factor in the marketability and usefulness of the equipment.
The high-speed storage and retrieval required for payload databases necessitates their storage in random access memory (RAM). RAM, however, will lose its memory contents if its power is interrupted. If power is interrupted, either at start-up or at a failure, the STP must either reestablish the contents of the payload databases or preserve the database content prior to the start-up or failure.
Conventional approaches to preserving or restoring a payload database after failure or start-up have several drawbacks. One approach uses non-volatile random access memory (NV-RAM) on the network payload processor card to preserve the contents of the payload database. If power is lost, the NV-RAM still stores the payload database and can help in rapidly returning the payload processor card to operability. NV-RAM, however, is currently an order of magnitude more expensive than dynamic random access memory (DRAM), which cannot preserve data after losing its power.
A second approach to preserving or restoring a payload database uses a software algorithm to extract the necessary data from a persistent, human-accessible database and download the extracted data to the DRAM that stores the payload database. This second approach, however, must extensively transform the data from the human-accessible database in order to attain the high-speed embedded form necessary for the payload database.
In light of the foregoing, there is a need for a method and system for restoring a database to a payload processor after a power interruption, or any event requiring a reloading or a refreshing of the database, that is relatively inexpensive to manufacture and does not require the extended transformation time.